Class: Minitest::Proptest::Property

Inherits:
Object
  • Object
show all
Includes:
Assertions
Defined in:
lib/minitest/proptest/property.rb

Overview

Property evaluation - status, scoring, shrinking

Defined Under Namespace

Classes: InvalidProperty

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Assertions

#property

Constructor Details

#initialize(test_proc, filename, methodname, random: Random.method(:new), max_success: 100, max_discard_ratio: 10, max_size: 0x100, max_shrinks: 0x7fffffffffffffff, previous_failure: []) ⇒ Property

Returns a new instance of Property.



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# File 'lib/minitest/proptest/property.rb', line 16

def initialize(
  # The function which proves the property
  test_proc,
  # The file in which our property lives
  filename,
  # The method containing our property
  methodname,
  # Any class which provides `rand` accepting both an Integer and a Range
  # is acceptable.  The default value is Ruby's standard Mersenne Twister
  # implementation.
  random: Random.method(:new),
  # Maximum number of successful cases before considering the test a
  # success.
  max_success: 100,
  # Maximum ratio of discarded tests per successful test before giving up.
  max_discard_ratio: 10,
  # Maximum amount of entropy to generate in a single run
  max_size: 0x100,
  # Maximum number of shrink attempts (default of half of max unsigned int
  # on the system architecture adopted from QuickCheck
  max_shrinks: 0x7fffffffffffffff,
  # Previously discovered counter-example.  If this exists, it should be
  # run before any test cases are generated.
  previous_failure: []
)
  @test_proc         = test_proc
  @filename          = filename
  @methodname        = methodname
  @random            = random.call
  @generator         = ::Minitest::Proptest::Gen.new(@random)
  @max_success       = max_success
  @max_discard_ratio = max_discard_ratio
  @max_size          = max_size
  @max_shrinks       = max_shrinks
  @status            = Status.unknown
  @trivial           = false
  @result            = nil
  @exception         = nil
  @calls             = 0
  @assertions        = 0
  @valid_test_cases  = 0
  @generated         = []
  @arbitrary         = nil
  @previous_failure  = previous_failure.to_a
  @local_variables   = {}
end

Instance Attribute Details

#assertions ⇒ Object

Returns the value of attribute assertions.



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# File 'lib/minitest/proptest/property.rb', line 14

def assertions
  @assertions
end

#calls ⇒ Object (readonly)

Returns the value of attribute calls.



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# File 'lib/minitest/proptest/property.rb', line 12

def calls
  @calls
end

#result ⇒ Object (readonly)

Returns the value of attribute result.



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# File 'lib/minitest/proptest/property.rb', line 12

def result
  @result
end

#status ⇒ Object (readonly)

Returns the value of attribute status.



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# File 'lib/minitest/proptest/property.rb', line 12

def status
  @status
end

#trivial ⇒ Object (readonly)

Returns the value of attribute trivial.



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# File 'lib/minitest/proptest/property.rb', line 12

def trivial
  @trivial
end

Instance Method Details

#explain ⇒ Object 



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# File 'lib/minitest/proptest/property.rb', line 69

def explain
  prop = if @status.valid?
           'The property was proved to satsfaction across ' \
             "#{@valid_test_cases} assertions."
         elsif @status.invalid?
           'The property was determined to be invalid due to ' \
             "#{@exception.class.name}: #{@exception.message}\n" \
             "#{@exception.backtrace.map { |l| "    #{l}" }.join("\n")}"
         elsif @status.overrun?
           "The property attempted to generate more than #{@max_size} " \
             "bytes of entropy, violating the property's maximum " \
             'size.  This might be rectified by increasing max_size.'
         elsif @status.unknown?
           'The property has not yet been tested.'
         elsif @status.interesting?
           info = 'A counterexample to a property has been found after ' \
                  "#{@valid_test_cases} valid " \
                  "example#{@valid_test_cases == 1 ? '' : 's'}.\n"
           var_info = if @local_variables.empty?
                        'Variables local to the property were unable ' \
                          'to be determined.  This is usually a bug.'
                      else
                        "The values at the time of the failure were:\n"
                      end
           vars = @local_variables
                  .map { |k, v| "\t#{k}: #{v.inspect}" }
                  .join("\n")

           info + var_info + vars
         elsif @status.exhausted?
           "The property was unable to generate #{@max_success} test " \
             'cases before generating ' \
             "#{@max_success * @max_discard_ratio} rejected test " \
             "cases.  This might be a problem with the property's " \
             '`where` blocks.'
         end
  trivial = if @trivial
              "\nThe test does not appear to use any generated values " \
                'and as such is likely not generating much value.  ' \
                'Consider reworking this test to make use of arbitrary ' \
                'data.'
            else
              ''
            end
  prop + trivial
end

#run! ⇒ Object 



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# File 'lib/minitest/proptest/property.rb', line 63

def run!
  rerun!
  iterate!
  shrink!
end